Abstract

The Transition or T-Zone is defined as an area in which water is too shallow for acquisition of marine seismic data with towed streamers, such as near the shoreline, marshes and lagoons with water depths of typically less than 5 ft and in a broader sense to the area of marshland and swamp that constitutes a swath of Southern Louisiana 30 to 50 mi wide, running parallel to the coastline.

Many of the Gulf Coast’s giant oil and gas discoveries have been made in the Transition Zone but the majority of these discoveries were made in the 1950s or earlier. 3D seismic data quality was notoriously of inferior quality because of the difficulties and cost of data acquisition across the land/sea interface and hindered by the presence of field facilities and infrastructure such as tank batteries, compressors and pipelines. Because of the high cost of acquisition, many of the earlier surveys were either compromised in terms of quality or limited to the crests and immediate flanks of salt domes, with little or no 3D data coverage between known fields.

The paper will focus on examples of some notable successes among the independents and will try to demonstrate that there is substantial untapped potential remaining in the T-Zone, not just in the “ultra-deep” plays but also at conventional depths and even in the “ultra-shallow” play, showing trap styles, and seismic and log data.